1276235 九、發明說明： 【發明所屬之技術領域】 本發明涉及一種以薄膜技術製成半導體晶片所用之方法 及以薄膜技術製成的半導體晶片。 【先前技術】 薄膜半導體晶片例如由文件EP 0 905 797 A2中已爲人所 知。爲了製成此種薄膜半導體晶片，須在一種生長基板上生 長活性之層序列，其適合用來發出光子。由於生長基板大部 •份都可吸收該活性之層序列所產生的光子之一部份，則活性 之層序列須與生長基板相分離且施加在另一載體上以使光 效益提高。載體和活性之層序列之間存在著一反射層。載體 和活性之層序列之間的連接藉由黏合或焊接來達成。通常使 用固定的載體（例如，砷化鎵-或鍺晶圓），但其缺點是：載體 厚度由於斷裂之危險性而不能任意減小。特別是以傳統方法 不易使載體厚度下降至1 00微米以下。這對薄膜半導體晶片 之構造高度上的極限是一種障礙。 ® 習知之薄膜半導體晶片之其它缺點是：活性之層序列由基 板轉移至載體時不易操控。 爲了防止上述之問題，DE 1 00 40 448 A1中建議：一種強 化層和輔助載體層在背面上施加至接觸層上。輔助載體層可 取代傳統方法中所用的機械式載體且可使活性之層序列之 操控較簡單。 當然，上述方法在活性之層序列轉移至晶圓位準上的輔助 載體上之後不可能（或只能很昂貴地）對後來所製成的全部 1276235 之薄膜半導體晶片進行測試。 裊 【發明內容】 a 本發明的目的是提供一種以薄膜技術簡易地製成高度較 小的半導體晶片所用之方法，其中可對後來在晶圓位準上所 形成的薄膜半導體晶片簡易地進行測試。此外，本發明的目 的是提供一高度較小的薄膜半導體晶片，其同時具有良好的 1 機械穩定性。 上述目的以申請專利範圍第1項的方法和第1 6項的半導 9體晶片來達成。本方法和半導體晶片之其它有利的形式描述 在申請專利範圍第2至1 5項或第1 7至23項中。 本發明中該薄膜半導體晶片之製造方法包含以下各步驟： -施加一種活性之磊晶-層序列至生長基板上，此層序列 適合用來產生電磁輻射， _在活性之層序列上形成一種導電之反射式接觸材料層， -在生長基板上使活性之層序列和該接觸材料層結構化 成互相分離之活性層堆疊， ^ -在該導電之反射式接觸材料層上施加一種可撓性的導 電箔，以及 -將該生長基板之至少一部份去除。 另一方式是藉由遮罩技術以施加該接觸材料層且進行橫 向之結構化’然後只使該接觸材料層下方之活性之層序列被 結構化’使活性的層堆疊上分別存在著一種接觸材料層。此 接觸材料層較佳是包含一種金屬。 本方法的優點是：薄膜半導體晶片之設有接觸材料層之背 1276235 面經由可撓性的箔而互相導電性地連接著’且因此使每一薄 % 膜半導體晶片都可分別藉助於其面對該接觸材料層之前側 < 上的另一接觸區而簡易地在晶圓位準上進行測試。 使用可撓性的導電箔作爲輔助載體層時所具有的優點 是：污染（例如，微粒之形式）時由於其較高的可延展性，則 在箔和層複合物堆疊之間只會在污染物周圍形成較小的干 擾半徑。由於污染所造成的效益上之損失因此較小。 此外，使用可撓性的箔作爲載體時可使薄膜半導體晶片之 •構造上的高度較小，此乃因可撓性的箔之厚度較固定之載體 的厚度還小，其中斷裂的危險性通常隨著厚度之變小而大大 地增加。 薄膜半導體晶片之小的構造高度可使薄膜半導體晶片上 稍後在放置其它元件於組件外殻內部中時較容易，這些元件 例如與發光材料有關，其可對該薄膜半導體晶片所發出的輻 射之波長進行轉換。此種所謂波長轉換材料例如已描述在 WO 98/ 1 27 5 7 A1中，其已揭示之內容收納於此以作爲參 ®考。同樣可行的是直接在薄膜半導體晶片上施加多個可造成 射束的光學元件，例如，透鏡。 利用本發明的方法，則例如可製成薄膜發光二極體晶片。 薄膜發光二極體晶片之特徵特別是： -在磊晶層序列之面向載體元件之第一主面（其可產生電 磁輻射）上施加或形成一種反射層，此反射層使磊晶層序列 中所產生的電磁輻射之至少一部份反射回到磊晶層序列 中；以及 1276235 β -磊晶層序列所具有的厚度是在2 Ο微米或更小的範圍 中，特別是在1 〇微米的範圍中。 在特別有利的情況下，磊晶層序列包含至少一種半導體 層，其具有至少一個面，此面則具有一種混合結構，其在理 想情況下會使光束在磊晶層序列中形成一種幾乎是隨機 (ergodic)之分佈，即’光束具有一種儘可能是隨機的雜散分 佈。 薄膜發光二極體之基本原理例如已描述在I. Schnitzer et • al·，Appl· Phys. Lett· 63 (16)，18· October 1 993，2174-2176 中，其已揭示的內容收納於此以作爲參考。 薄β吴發光一*極體晶片很接近於一種藍伯德（Lambertic)表 面發射器。 目前此種薄膜發光二極體晶片較佳是以氮化物-化合物半 導體材料爲主。以氮化物-化合物半導體材料爲主在此處的 意義是：活性之磊晶層序列或至少一活性之磊晶層序列包含 一種氮化物-III/V-化合物半導體材料，較佳是 ’ AlnGamIni.n-mN，其中 OSnSl，〇‘mSl 且 n + mSl。此種材 料未必含有上述公式所示之正確的數學成份。反之，其可具 有一種或多種摻雜物質以及其它的成份，其基本上未改變 AlnGamIni_n_mN-材料之物理性質。但爲了簡單之故，當各成 份有一部份可由少量的其它材料所取代時，則上述公式只包 含晶格之主要成份（Al，Ga，In，N)。 在本發明之方法之一特別有利的實施形式中，可撓性的導 電箔是一種石碳箔，其例如在文件US 5 695 847和US 5 849 1276235 1 3 0中已爲人所知，其已揭示的內容收納於此處以作爲參考。 石碳箔之特徵除了價格較低以外特別有利的是一種高的 導熱性和導電性以及一種小的厚度。此外，石碳箔之優點 是：其藉由施加較小的壓力和溫度即可與層複合物（包括磊 晶層序列和接觸材料層）相連接。這樣在連接步驟時可使活 性之層堆疊受損之危險性減小。又，薄膜半導體晶片（其包 含一種石碳箔以作爲最下層）可簡單地以傳統方式安裝在外 殻中且達成電性上的接觸。石碳箔之高的導熱性可有利地使 •熱有效地排出，熱是薄膜半導體晶片操作時所產生者。 導電箔之厚度較佳是小於1 〇〇微米。由於相對於固定之載 體而言箔具有可撓性，則可達成上述較小的載體厚度。 爲了保護薄膜半導體晶片使不受腐蝕，則須在層複合物堆 疊之在結構化時成爲空著的側面之至少一些部份上施加一 種鈍化層，其例如含有氮化矽。鈍化層除了其保護功能之外 亦可滿足其它的目的，例如，電性上的隔離。 在本發明之方法的另一有利的形式中，在導電之反射式接 β觸材料層上施加一種導電之強化層，其例如含有金屬。此強 化層一方面用來使活性之層序列穩定且另一方面可經由背 面而使薄膜半導體晶片稍後達成一種電性上的接觸作用。 在另一有利的實施形式中，在去除該生長基板之前一種固 定式輔助載體可與一可撓性的導電箔相連接。此種額外的固 定式輔助載體可使層複合物強化，使其可導入一般之測試系 統中或處理設備中且在晶圓-位準上加工。 使用一種石碳箔作爲層複合物和固定式輔助載體之間的 1276235 連接層時特別是可提供下述的優點：其可與多種處理技術相 容。因此，這例如與真空中的黏合材料層不同，本發明中在 環境周圍不會造成氣體形式之干擾性物皙。 在生長基板去除之後，以傳統方式分別在活性的層序列之 先前位於生長基板上之此側上施加其它之導電接觸層。這些 導電接觸層例如含有一種金屬。這些接觸層分別是每一薄膜 半導體晶片之第二電性接觸位置，其上例如可施加一種連結 線。 • 此外，較佳是在上述之導電接觸位置上施加一種中間載體 且將可撓性的導電箔去除。各薄膜半導體晶片因此可互分離 而固定在此中間載體上，由此中間載體上可簡單地取出（例 如，以傳統的Pick-and-Place機器）薄膜半導體晶片且進行 組裝。此中間載體例如可爲另一種箔（例如，鋸齒箔）。在此 種鋸齒箔上例如在藉由晶圓切鋸以進行切割之前可將半導 體晶片固定在晶圓複合物中。 稍後之薄膜半導體晶片之側面較佳是可整面上設有鈍化 Φ層。這可適當地在該導電箔與固定式輔助載體相連接且該生 長基板剝除之後才進行。固定式輔助載體使層複合物穩定， 該層複合物在正規的處理設備中可設有鈍化層。 薄膜半導體晶片之切割同樣可適當地以下述方式達成：在 活性之層堆疊之此側（其原來是與生長基板相連接）上施加 另一中間載體（例如，箔或鋸齒箔）且將該可撓性導電箔去 除。本發明的薄膜半導體晶片包含： -一活性之層序列，其適合用來產生電磁輻射， -10- 1276235 —在該活性之層序列上的導電之反射式接觸材料層， -在該導電之反射式接觸材料層上之可撓式導電箔’其用 作載體層。 上述之薄膜半導體晶片之優點是··其構造高度小，較佳是 小於1 5 0微米且特別是小於1 〇〇微米。因此，其可安裝在外 殼中而不會有較高的斷裂危險性。由於較小的構造上的高 度，則此種薄膜半導體晶片特別適合用來與波長轉換材料一 起安裝在尺寸很小的外殼中。 • 此外，上述之薄膜半導體晶片在背面上可簡單地經由可撓 性的導電箔而達成電性上的接觸作用。 使用可撓性的導電箔時，在操控和組裝該薄膜半導體晶片 之情況下同時可使斷裂之危險性下降。 在一特別有利的實施形式中，可撓性之導電箔是一種石碳 箔，其特徵是特別高的導電性和導熱性以及價格較低。 在另一有利的實施形式中，在導電之反射式接觸材料層上 存在著一種導電之強化層，其用來使活性的層序列更強化且 #同時可經由可撓性的導電箔使薄膜半導體晶片達成一種背 面上的接觸作用。 導電之反射式接觸材料層和導電之強化層較佳是都含有 一種金屬。 此外，本發明的薄膜半導體晶片之側面較佳是整面上設有 一種鈍化層。此種薄膜半導體晶片特別適合用來作電性上的 接觸而不需導線。因此，此種薄膜半導體晶片可在背面上進 行接觸，此時施加一電性連接導體’其例如位於晶片載體上 -11- 1276235 或本身形成一種晶片載體（例如，導線架）。薄膜半導體晶片 在前側上可藉由一種整面施加而成-或藉由結構化施加而成 之導電層而進行接觸，此導電層可適當地使薄膜半導體晶片 所發出的電磁輻射良好地透過。 本發明之方法或半導體晶片之其它優點和有利的實施形 式以下將依據第la至If圖，第2a至2c圖，第3a和3b圖 以及第4圖來詳述。 【實施方式】 § 各實施例和圖式中相同或作用相同之組件分別設有相同 的參考符號。各圖式之各元件中特別是層厚度之大小和層厚 度之比例基本上未依比例繪出。反之，爲了更易了解起見有 一部份是以放大方式繪出。 實施例1 依據實施例1之方法，第一步驟中在生長基板3上施加一 種活性之層序列20(第1 a圖）。這在較佳之實施形式中例如 藉由在藍寶石-或SiC-基板上磊晶生長多個不同之層來達 β成’這些層由氮化物_ I〗I/V -化合物半導體材料所構成，較佳 是由 AlnGamlm-n-mN，其中 OSnS 1，OSmS 1 且 n + mS 1 所構 成。當然，上述之成份中除了 In，A1及/或Ga和N之外亦可 包含其它的元素。 上述適合用來產生電磁輻射之活性的層序列例如可具有 —種傳統的Ρ η -接面，雙異質結構，單一-量子井結構（s Q W -結構）或多重-量子井結構（MQW-結構）。這些結構已爲此行的 專豕所知悉’此處因此不再詳述。適當的量子井結構例如由 1276235 ，w 0 0 1 /3 9 2 8 2中已爲人所知，其所揭示的內容收納於此處以 作爲參考。 然後’在活性之層序列2 0上形成一種導電之反射式接觸 材料層4 0 (第1 b圖）。此接觸材料層4 〇在稍後之薄膜半導體 晶片1中另外可用來發出輻射（其由活性之層序列2 〇而發射 至接觸材料層40之方向中）至薄膜半導體晶片1之與接觸材 料層4 0之相面對的輻射側，以使輻射效益提高。 接觸材料層4 0可整面含有一種金屬材料，例如，銀，金 Φ或鋁，其以蒸鍍施加而成。此外，可使用介電質反射器，其 由多個具有電性接觸區之介電質層所構成。 適當的反射器例如由W Ο 0 1 / 8 2 3 8 4中已爲人所知，其所 揭示的內容收納於此處以作爲參考。 該接觸材料層4 0同時作爲活性之層序列2 0用之背面之接 觸材料層。活性之層序列20和導電之反射式接觸材料層40 總共具有的厚度例如可爲8微米。 在下一個步驟中，由層複合物（其具有活性之層序列20和 β接觸材料層40)而在生長基板1上形成互相隔離之活性之層 堆疊2，其分別具有導電之反射式接觸材料層4(第lc圖）。 這例如藉由濕式化學蝕刻或乾式蝕刻來達成。 另一方式是該接觸材料層40亦可橫向地被結構化（這例 如藉由遮罩來進行）而施加在活性的層序列20上且此活性的 層序列20隨後被結構化成活性的層堆疊2，使一種導電之 反射式接觸材料層4位於一活性之層堆疊2上。 然後，在導電之反射式接觸材料層4上施加一種可撓式之 1276235 導電箔6 ’其例如可爲一種厚度介於3 0和8 0微米之間的石 碳范。 石碳箔所提供之優點是：其在溫度小於或等於150GC時且 在較小的壓力（大約1巴）下可與層複合物堆疊2 1相連接。 爲了進行該連接過程，可施加石碳箔在一種支件上。因 此，在此過程中石碳箔亦未與該支件相連接，例如，一種抗 黏合箔（例如，Teflon)可施加在支件和石碳箔之間。當然， 此種抗黏合箔在連接過程中亦可用在其它位置上，在這些位 馨置上存在以下的危險性：石碳箔會不小心地與其它面形成連 接。 在下一步驟中，去除該生長基板1，其上生長著該活性之 層序列20 ’這例如藉由一種雷射剝離過程（其例如已描述在 WO 98/14986中）來達成。如第ie圖所示，活性之層堆疊2 及一種位於背面之導電之反射式接觸材料層4現在相鄰地 處於可撓性之導電箔6上。 另一種步驟是可在層複合物堆疊2 1被結構化之後在層複 •合物堆疊2 1之側面上至少一部份形成一種鈍化層5，如第 1 f圖所不，其例如可由氮化矽，氧化錦，氮化錫或氧化之氮 化矽所構成。 薄膜半導體晶片1可藉助於傳統方法（例如，雷射切割， 水射束切割或切鋸）以藉由箔（6)之分離來切割而成。 薄膜半導體晶片1(其在背面上設有石碳箔6)可簡單地藉 由施加壓力和溫度而固定在外殻中。另一方式是此種薄膜半 導體晶片1藉由黏合而與外相連接。 -14- 1276235 實施例2 類似於實施例1，進行三個步驟：活性之層序列20之製 造，施加一導電之接觸材料層4 0和使上述二種層結構化成 層複合物堆疊2 1。與實施例1不同的是，現在須在層複合 物堆疊2 1之接觸材料層4上施加另一導電之強化層7，因 此現在包括至少三種層。導電之強化層7例如可由金屬材料 所構成，此材料以電鍍方式施加而成。 活性之層序列2以及導電之反射式接觸材料層4和金屬強 鲁化層7總共之厚度例如可介於20微米和25微米之間。 在層序列20和導電之反射式接觸材料層40結構化成互相 分離之活性層複合物堆疊2且施加該上述之金屬強化層7之 後，在活性之層堆疊2之裸露之側面上施加一種鈍化層5且 在對應於活性之層堆疊2之金屬強化層7上施加一種石碳箔 6(第2a圖）。 爲了進一步強化上述方式所產生的層複合物，則可在石碳 箔6之背面上又藉由施加壓力和溫度以形成另一穩定之固 ®定式輔助載體8，其厚度例如介於1 00和1 5 0微米之間。亦 可使用較厚之載體。 該固定式輔助載體8可使層複合物之操控更簡易且在傳 統之LED-製造設備中使層複合物作進一步之處理。同時， 若該固定式輔助載體由導電材料（例如，鉬，鉬或鎢）所構 成，則稍後形成的薄膜半導體晶片1仍可在晶圓位準上在背 面作電性接觸。這樣可以傳統之測量工具對製作在一晶圓上 的全部之薄膜半導體晶片1進行測試。 -15- 1276235 , 在下一步驟中’又去除該生長基板3(第2b圖）且在活性之 ^層堆疊2之前側（其先前是與生長基板1相連接）上形成導電 之金屬接觸區9，其例如可包含以蒸鍍形成的銀，金或鋁。 然後，以傳統測試方法在晶圓複合物中對全部之薄膜半導 體晶片1進行測試，各薄膜半導體晶片1分別由活性之層堆 豐2，導電之接觸材料層4，強化層7，石碳箔6和接觸區9 所構成。 如第2c圖所示，現在可在導電之接觸區9之前側上施加 鲁一種中間載體1 〇，其可爲一種箔，就像其在晶圓切鋸中所 用者一樣。藉由選擇性地去除石碳箔6(例如，以濕式化學方 法）’則薄膜半導體晶片1又可由固定式輔助載體8去除且 同時被切割。各別之薄膜半導體晶片1現在準備進行傳統之 再處理過程，例如，安裝在導線架上及/或外殻上。 實施例3 如實施例1和2中所述，層複合物堆疊2 1製作在晶圓複 合物中，其中每一層複合物堆疊21都包含一活性之層堆疊 β 2和導電之反射式接觸材料層4，其上可選擇性地存在著另 一導電之強化層7。層複合物堆疊2 1在生長基板3去除之 後存在導電箔6上，導電箔6是與固定式輔助載體8相連接。 如第3 a圖所示，鈍化層5亦整面施加在稍後所形成的薄 膜半導體晶片1之側面上，各薄膜半導體晶片1分別由活性 之層堆疊2，導電之接觸材料層4和金屬強化層7所構成。 適當的方式是在層複合物經由石碳箔6而與固定式輔助 載體8相連接之後施加該鈍化層5。然後，薄膜半導體晶片 1276235 _ 1藉由選擇性地去除石碳箔6而切割。薄膜半導體晶片1然 後存在著整個側面之絕緣區。因此，稍後已不需另一鈍化 層。此種鈍化層通常在薄膜半導體晶片1中進行，其依據標 準方法製成。 第3 b圖顯示一種薄膜半導體晶片1，其整個側面是位於 可撓式導電箔6上的鈍化層5，箔6是與固定式輔助載體8 相連接。固定式輔助載體8若由導電材料（例如，鉬）所構成， 則第3 b圖顯示一種狀態，其中稍後之薄膜半導體晶片1同 _時被測試。 實施例4 第4圖中顯示薄膜半導體晶片1，其由活性之層堆疊2所 構成’層堆疊2之背面上存在著導電之反射式接觸材料層 4 ’其亦藉由金屬強化層7來強化。薄膜半導體晶片1之側 面因此整面上是以鈍化層5來覆蓋。 此種薄膜半導體晶片1特別適合用來在施加在適當的晶 片載體1 1上之後作爲電性接觸之用而不需導線。 ® 因此，薄膜半導體晶片1施加在一適當的晶片載體1 1 (例 如’電路板）上。晶片載體可適當地含有導電結構1 2以對稍 後之薄膜半導體晶片1進行背面上的接觸，晶片載體1 1之 其餘部份是由絕緣材料（例如，塑料）所構成。薄膜半導體晶 片定位在晶片載體1 1之導電結構1 2上且隨後藉由整面上施 加一種導電層1 3而可經由薄膜半導體晶片1在晶片載體！ i 的表面上達成電性上的接觸。導電層13適當的方式是由一 種對該薄膜半導體晶片1所發出的電磁輻射具有高透過性 I276235 、 的材料（例如，氧化銦錫（IT 0)或氧化鋅）所構成。 ^ 此處須指出，上述之接觸方法（其中不需導線）可視爲一種 獨立的發明。 爲了完整性，此處須指出：本發明當然不限於上述的實施 例’所有以上述基本原理之一般部份爲主之實施例都在本發 明的範圍中。同時須指出：不同實施例中的不同的元件可互 - 相組合而未脫離本發明的基本構想。 【圖式簡單說明】 ，鲁第la至If圖 本方法一實施例之不同階段中晶圓複合物之 - 切面圖。 第2a至2c圖 本方法另一實施例之不同階段中晶圓複合物 之切面圖。 第3 a和3 b圖 本方法之再另一實施例之不同階段中晶圓複 合物之切面圖。 第4圖 本發明之薄膜半導體晶片之切面圖，其施加在晶片 載體上且可作電性上的接觸。 •【主要元件符號說明】 1 薄 膜 半 導 體 晶 片 2 活 性 之 層 堆 疊 20 活 性 之 層 序 列 21 層 複 合 物 堆 疊 3 生 長 基 板 4 導 電 之 反 射 式 接觸材料層 5 鈍 化 層 -18- 1276235 6 可 撓 式 導 電 箔 7 金 屬 強 化 層 8 固 定 式 輔 助 載 體 9 前 側 之 導 電 接 觸 區 10 另 —* 箔 11 晶 片 載 體 12 晶 片 載 體 上 的 導 電 結構 13 晶 片 接 觸 用 的 導 電 層 -19-1276235 IX. Description of the Invention: [Technical Field] The present invention relates to a method for fabricating a semiconductor wafer by a thin film technique and a semiconductor wafer fabricated by a thin film technique. [Prior Art] A thin film semiconductor wafer is known, for example, from the document EP 0 905 797 A2. In order to produce such a thin film semiconductor wafer, a layer sequence of active layers is grown on a growth substrate which is suitable for emitting photons. Since most of the growth substrate absorbs a portion of the photons produced by the active layer sequence, the active layer sequence must be separated from the growth substrate and applied to another carrier to enhance optical efficiency. There is a reflective layer between the carrier and the active layer sequence. The connection between the carrier and the active layer sequence is achieved by bonding or welding. A fixed carrier (e.g., gallium arsenide- or germanium wafer) is usually used, but has the disadvantage that the thickness of the carrier cannot be arbitrarily reduced due to the risk of breakage. In particular, it is difficult to reduce the thickness of the carrier to less than 100 μm in the conventional manner. This is an obstacle to the height limit of the construction of the thin film semiconductor wafer. A further disadvantage of the conventional thin film semiconductor wafers is that the active layer sequence is not easily manipulated when transferred from the substrate to the carrier. In order to prevent the above problems, it is proposed in DE 1 00 40 448 A1 that an reinforced layer and an auxiliary carrier layer are applied to the contact layer on the back side. The auxiliary carrier layer can replace the mechanical carrier used in the conventional method and can make the manipulation of the active layer sequence simpler. Of course, the above method is not possible (or only very expensive) to test all of the subsequently fabricated 1276235 thin film semiconductor wafers after the active layer sequence is transferred to the auxiliary carrier on the wafer level. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for easily fabricating a semiconductor wafer of a relatively small height by a thin film technique in which a thin film semiconductor wafer formed later on a wafer level can be easily tested. . Furthermore, it is an object of the present invention to provide a thin film semiconductor wafer having a high degree of mechanical stability at the same time. The above object is achieved by the method of claim 1 and the semiconductor semiconductor wafer of item 16. Other advantageous forms of the method and semiconductor wafer are described in claims 2 to 15 or items 17 to 23. The method for fabricating a thin film semiconductor wafer of the present invention comprises the following steps: - applying an active epitaxial layer sequence to a growth substrate, the layer sequence being suitable for generating electromagnetic radiation, forming a conductive layer on the active layer sequence a layer of reflective contact material, - structuring the active layer sequence and the layer of contact material on the growth substrate into a separate active layer stack, ^ - applying a flexible conductive layer on the conductive reflective contact material layer a foil, and - removing at least a portion of the growth substrate. Another way is by masking the technique to apply the layer of contact material and perform lateral structuring 'then only the layer sequence of the active layer below the layer of contact material is structured' so that there is a contact on the active layer stack Material layer. Preferably, the layer of contact material comprises a metal. The method has the advantage that the back surface 1276235 of the thin film semiconductor wafer provided with the contact material layer is electrically connected to each other via the flexible foil' and thus each thin film semiconductor wafer can be individually coated by its surface The wafer level is simply tested on the previous contact area on the front side of the contact material layer. The use of a flexible conductive foil as an auxiliary carrier layer has the advantage that contamination (for example in the form of particles) is only contaminated between the foil and the layer stack due to its high ductility. A small interference radius is formed around the object. The loss of benefits due to pollution is therefore small. In addition, when a flexible foil is used as the carrier, the structural height of the thin film semiconductor wafer can be made small because the thickness of the flexible foil is smaller than the thickness of the fixed carrier, and the risk of breakage is usually It greatly increases as the thickness becomes smaller. The small construction height of the thin film semiconductor wafer can be made easier on the thin film semiconductor wafer later when other components are placed in the interior of the component housing, such as in relation to the luminescent material, which can emit radiation to the thin film semiconductor wafer. The wavelength is converted. Such a so-called wavelength converting material has been described, for example, in WO 98/1 27 5 7 A1, the disclosure of which is incorporated herein by reference. It is also possible to apply a plurality of optical elements which can cause a beam, such as a lens, directly on the thin film semiconductor wafer. With the method of the present invention, for example, a thin film light emitting diode wafer can be fabricated. The thin-film light-emitting diode wafer is characterized in particular by: - applying or forming a reflective layer on the first main surface of the epitaxial layer sequence facing the carrier element which generates electromagnetic radiation, the reflective layer being in the epitaxial layer sequence At least a portion of the generated electromagnetic radiation is reflected back into the epitaxial layer sequence; and the 1276235 β-epitaxial layer sequence has a thickness in the range of 2 μm or less, particularly at 1 μm. In the scope. In a particularly advantageous case, the epitaxial layer sequence comprises at least one semiconductor layer having at least one face which has a hybrid structure which ideally causes the beam to form an almost random sequence in the epitaxial layer sequence. The distribution of (ergodic), that is, the beam has a stray distribution that is as random as possible. The basic principle of a thin film light-emitting diode is described, for example, in I. Schnitzer et al., Appl. Phys. Lett 63 (16), 18 October 1 993, 2174-2176, the contents of which are hereby incorporated herein. For reference. The thin beta Wu luminescence-anode wafer is very close to a Lambert surface emitter. At present, such a thin film light-emitting diode wafer is preferably a nitride-compound semiconductor material. The main meaning of the nitride-compound semiconductor material here is that the active epitaxial layer sequence or at least one active epitaxial layer sequence comprises a nitride-III/V-compound semiconductor material, preferably 'AlnGamIni. n-mN, where OSnSl, 〇'mSl and n + mSl. Such materials do not necessarily contain the correct mathematical components as indicated by the above formula. Conversely, it may have one or more dopant species and other components that do not substantially alter the physical properties of the AlnGamIni_n_mN-material. However, for the sake of simplicity, when a portion of each component can be replaced by a small amount of other materials, the above formula contains only the main components of the crystal lattice (Al, Ga, In, N). In a particularly advantageous embodiment of the method, the flexible conductive foil is a stone carbon foil, which is known, for example, from the documents US Pat. The disclosures are hereby incorporated by reference. In addition to the lower price, the characteristics of the stone carbon foil are particularly high in thermal conductivity and electrical conductivity as well as a small thickness. In addition, the advantage of stone carbon foil is that it can be joined to the layer composite (including the epitaxial layer sequence and the contact material layer) by applying less pressure and temperature. This reduces the risk of damage to the active layer stack during the joining step. Further, a thin film semiconductor wafer (which contains a stone carbon foil as the lowermost layer) can be simply mounted in the outer casing in a conventional manner and electrically contacted. The high thermal conductivity of the stone carbon foil advantageously allows the heat to be efficiently discharged, which is generated when the thin film semiconductor wafer is operated. The thickness of the conductive foil is preferably less than 1 〇〇 micrometer. The smaller carrier thickness described above can be achieved due to the flexibility of the foil relative to the fixed carrier. In order to protect the thin film semiconductor wafer from corrosion, a passivation layer, for example containing tantalum nitride, is applied over at least some of the side of the layer composite stack which becomes vacant during structuring. In addition to its protective function, the passivation layer can serve other purposes, such as electrical isolation. In a further advantageous form of the method according to the invention, an electrically conductive reinforcing layer, for example comprising a metal, is applied to the electrically conductive reflective beta-contact material layer. This reinforced layer serves on the one hand to stabilize the active layer sequence and on the other hand allows the thin film semiconductor wafer to later achieve an electrical contact via the back side. In a further advantageous embodiment, a fixed auxiliary carrier can be connected to a flexible electrically conductive foil before the growth substrate is removed. This additional fixed auxiliary carrier allows the layer composite to be reinforced so that it can be introduced into a typical test system or processing equipment and processed on a wafer-level. The use of a stone carbon foil as the 1276235 tie layer between the layer composite and the fixed auxiliary carrier provides, in particular, the advantage that it can be compatible with a variety of processing techniques. Thus, for example, unlike the layer of adhesive material in a vacuum, the present invention does not cause disturbing substances in the form of gases around the environment. After the removal of the growth substrate, other conductive contact layers are applied in a conventional manner on the side of the active layer sequence which was previously on the growth substrate. These electrically conductive contact layers contain, for example, a metal. These contact layers are respectively a second electrical contact location of each of the thin film semiconductor wafers to which, for example, a bonding line can be applied. • Further, it is preferred to apply an intermediate carrier at the above-mentioned conductive contact position and remove the flexible conductive foil. The thin film semiconductor wafers are thus detachable from each other and fixed to the intermediate carrier, whereby the thin film semiconductor wafer can be easily taken out (for example, in a conventional Pick-and-Place machine) and assembled on the intermediate carrier. This intermediate carrier can for example be another foil (for example a serrated foil). The semiconductor wafer can be secured to the wafer composite on such a sawtooth foil, for example, by wafer sawing for cutting. Preferably, the side of the thin film semiconductor wafer is provided with a passivation Φ layer on the entire surface. This can be suitably performed after the conductive foil is attached to the fixed auxiliary carrier and the growth substrate is stripped. The fixed auxiliary carrier stabilizes the layer composite, which layer may be provided with a passivation layer in a conventional processing apparatus. The dicing of the thin film semiconductor wafer can likewise be suitably achieved by applying another intermediate carrier (for example a foil or sawtooth foil) on the side of the active layer stack which was originally connected to the growth substrate and The flexible conductive foil is removed. The thin film semiconductor wafer of the invention comprises: - an active layer sequence suitable for generating electromagnetic radiation, -10- 1276235 - a layer of electrically conductive reflective contact material on the active layer sequence, - a reflection at the conductive A flexible conductive foil on the layer of contact material is used as a carrier layer. The above thin film semiconductor wafer has the advantage that its construction height is small, preferably less than 150 μm and especially less than 1 μm. Therefore, it can be installed in the outer casing without a high risk of fracture. Due to the small structural height, such thin film semiconductor wafers are particularly suitable for use in mounting in a small size housing together with the wavelength converting material. • In addition, the above-mentioned thin film semiconductor wafer can be electrically contacted on the back surface simply via a flexible conductive foil. When a flexible conductive foil is used, the risk of breakage can be reduced at the same time in the case of handling and assembling the thin film semiconductor wafer. In a particularly advantageous embodiment, the flexible electrically conductive foil is a stone carbon foil characterized by a particularly high electrical and thermal conductivity and a low price. In a further advantageous embodiment, a conductive reinforcing layer is present on the electrically conductive reflective contact material layer, which serves to strengthen the active layer sequence and at the same time to form a thin film semiconductor via a flexible conductive foil. The wafer achieves a contact on the back side. Preferably, the electrically conductive reflective contact material layer and the electrically conductive reinforcement layer comprise a metal. Further, it is preferable that the side surface of the thin film semiconductor wafer of the present invention has a passivation layer on the entire surface. Such thin film semiconductor wafers are particularly suitable for electrical contact without the need for wires. Thus, such a thin film semiconductor wafer can be contacted on the back side, in which case an electrical connection conductor ' is placed, for example, on the wafer carrier -11-1276235 or itself forms a wafer carrier (e.g., lead frame). The thin film semiconductor wafer can be contacted on the front side by a full surface application or by a structured application of a conductive layer which suitably transmits the electromagnetic radiation emitted by the thin film semiconductor wafer well. Other advantages and advantageous embodiments of the method or semiconductor wafer of the present invention will be described in more detail below in accordance with Figs. 1a to 2c, Figs. 3a and 3b, and Fig. 4. [Embodiment] § The same or similar components in the respective embodiments and the drawings are respectively provided with the same reference numerals. In particular, the ratio of the layer thickness and the layer thickness of the various elements of the various figures are not drawn to scale. On the contrary, in order to make it easier to understand, some of them are drawn in an enlarged manner. Example 1 According to the method of Example 1, an active layer sequence 20 (Fig. 1a) was applied to the growth substrate 3 in the first step. In a preferred embodiment, for example, by epitaxially growing a plurality of different layers on a sapphire- or SiC-substrate to form a β-layer, these layers are composed of a nitride-I/V-compound semiconductor material. Preferably, it is composed of AlnGamlm-n-mN, wherein OSnS 1, OSmS 1 and n + mS 1 . Of course, the above components may contain other elements in addition to In, A1 and/or Ga and N. The layer sequences described above which are suitable for generating the activity of electromagnetic radiation may, for example, have a conventional Ρ-junction, a double heterostructure, a single-quantum well structure (s QW-structure) or a multiple-quantum well structure (MQW-structure) ). These structures have been known for the expertise of this line. 'Therefore, it will not be detailed here. Suitable quantum well structures are known, for example, from 1276235, w0 0 1 /3 9 2 2 2 , the disclosure of which is incorporated herein by reference. A conductive reflective contact material layer 40 (Fig. 1b) is then formed on the active layer sequence 20. This contact material layer 4 is additionally used in a later thin film semiconductor wafer 1 to emit radiation (which is emitted from the active layer sequence 2 into the direction of the contact material layer 40) to the contact material layer of the thin film semiconductor wafer 1. The radiation side of the 40° phase faces to improve the radiation efficiency. The contact material layer 40 may have a metal material, for example, silver, gold Φ or aluminum, which is applied by evaporation. Further, a dielectric reflector can be used which is composed of a plurality of dielectric layers having electrical contact regions. Suitable reflectors are known, for example, from W Ο 0 1 / 8 2 3 8 4, the disclosure of which is incorporated herein by reference. The contact material layer 40 serves as the contact material layer on the back side of the active layer sequence 20. The active layer sequence 20 and the electrically conductive reflective contact material layer 40 have a total thickness of, for example, 8 microns. In a next step, a layer stack 2 of mutually isolated active layers is formed on the growth substrate 1 by a layer composite having an active layer sequence 20 and a beta contact material layer 40, each having a conductive reflective contact material layer 4 (Fig. lc). This is achieved, for example, by wet chemical etching or dry etching. Alternatively, the layer of contact material 40 can also be applied laterally (for example by means of a mask) on the active layer sequence 20 and the active layer sequence 20 can then be structured into an active layer stack. 2. A conductive reflective contact material layer 4 is placed on an active layer stack 2. A flexible 1276235 conductive foil 6' is then applied over the electrically conductive reflective contact material layer 4, which may for example be a stone carbon having a thickness between 30 and 80 microns. The stone carbon foil provides the advantage that it can be joined to the layer composite stack 21 at a temperature of less than or equal to 150 GC and at a relatively low pressure (about 1 bar). In order to carry out the joining process, a stone carbon foil can be applied to a support. Therefore, the stone carbon foil is not attached to the support during this process. For example, an anti-adhesive foil (e.g., Teflon) can be applied between the support and the stone carbon foil. Of course, such anti-adhesive foils can also be used in other locations during the joining process, and there is a risk that these carbon foils will inadvertently form joints with other surfaces. In the next step, the growth substrate 1 is removed, on which the active layer sequence 20' is grown, for example by a laser stripping process, which has for example been described in WO 98/14986. As shown in the Figure, the active layer stack 2 and a conductive reflective contact material layer 4 on the back side are now adjacent to the flexible conductive foil 6. Another step is to form at least a portion of the passivation layer 5 on at least a portion of the side of the layer stack 2 1 after the layer composite stack 21 has been structured, as in FIG. 1 f, which may, for example, be nitrogen. It is composed of bismuth oxide, bismuth oxide, tin nitride or oxidized tantalum nitride. The thin film semiconductor wafer 1 can be cut by separation of the foil (6) by means of a conventional method (for example, laser cutting, water jet cutting or sawing). The thin film semiconductor wafer 1 (which is provided with a stone carbon foil 6 on the back surface) can be fixed in the casing simply by applying pressure and temperature. Alternatively, the thin film semiconductor wafer 1 is bonded to the outer phase by bonding. - 14 - 1276235 Example 2 Similar to Example 1, three steps were carried out: the production of the active layer sequence 20, the application of a conductive contact material layer 40 and the structuring of the above two layers into a layer composite stack 21 . In contrast to the embodiment 1, it is now necessary to apply another electrically conductive reinforcing layer 7 on the layer of contact material 4 of the layer composite stack 21, thus now comprising at least three layers. The electrically conductive reinforcing layer 7 can be composed, for example, of a metal material which is applied by electroplating. The active layer sequence 2 and the electrically conductive reflective contact material layer 4 and the metal strongly-lubricated layer 7 may have a total thickness of, for example, between 20 microns and 25 microns. After the layer sequence 20 and the electrically conductive reflective contact material layer 40 are structured into separate active layer stacks 2 and the metal layer 7 is applied, a passivation layer is applied to the exposed side of the active layer stack 2 5 and a stone carbon foil 6 (Fig. 2a) is applied to the metal strengthening layer 7 corresponding to the active layer stack 2. In order to further strengthen the layer composite produced in the above manner, a pressure and temperature can be applied to the back surface of the stone carbon foil 6 to form another stable solid fixing auxiliary carrier 8, the thickness of which is, for example, between 100 and Between 1 50 microns. Thicker carriers can also be used. The fixed auxiliary carrier 8 makes handling of the layer composite easier and allows the layer composite to be further processed in conventional LED-manufacturing equipment. Meanwhile, if the fixed auxiliary carrier is composed of a conductive material (e.g., molybdenum, molybdenum or tungsten), the thin film semiconductor wafer 1 formed later can still make electrical contact on the back side at the wafer level. Thus, all of the thin film semiconductor wafers 1 fabricated on a wafer can be tested by a conventional measuring tool. -15- 1276235, in the next step 'removing the growth substrate 3 (Fig. 2b) and forming a conductive metal contact region 9 on the front side of the active layer stack 2 (which was previously connected to the growth substrate 1) It may, for example, comprise silver, gold or aluminum formed by evaporation. Then, all the thin film semiconductor wafers 1 are tested in the wafer composite by a conventional test method, and each of the thin film semiconductor wafers 1 is composed of an active layer 2, a conductive contact material layer 4, a strengthening layer 7, and a stone carbon foil. 6 and the contact zone 9 constitutes. As shown in Fig. 2c, an intermediate carrier 1 〇 can now be applied to the front side of the electrically conductive contact zone 9, which can be a foil, as it is used in wafer sawing. By selectively removing the stone carbon foil 6 (e.g., in a wet chemical method), the thin film semiconductor wafer 1 can be removed by the fixed auxiliary carrier 8 and simultaneously cut. The respective thin film semiconductor wafer 1 is now ready for a conventional reprocessing process, for example, on a lead frame and/or on a housing. Example 3 As described in Examples 1 and 2, a layer composite stack 21 was fabricated in a wafer composite wherein each layer of composite stack 21 comprised an active layer stack β 2 and a conductive reflective contact material. Layer 4, on which another electrically conductive reinforcing layer 7 is selectively present. The layer composite stack 21 is deposited on the conductive foil 6 after the growth substrate 3 is removed, and the conductive foil 6 is connected to the fixed auxiliary carrier 8. As shown in Fig. 3a, the passivation layer 5 is also applied over the entire surface of the thin film semiconductor wafer 1 to be formed later, and each of the thin film semiconductor wafers 1 is composed of an active layer stack 2, a conductive contact material layer 4 and a metal. The reinforcing layer 7 is composed of. A suitable way is to apply the passivation layer 5 after the layer composite has been joined to the stationary auxiliary carrier 8 via the stone carbon foil 6. Then, the thin film semiconductor wafer 1276235_1 is cut by selectively removing the stone carbon foil 6. The thin film semiconductor wafer 1 then has an insulating region on the entire side. Therefore, another passivation layer is no longer needed. Such a passivation layer is usually carried out in the thin film semiconductor wafer 1, which is produced in accordance with a standard method. Fig. 3b shows a thin film semiconductor wafer 1 whose entire side is a passivation layer 5 on a flexible conductive foil 6, which is connected to a stationary auxiliary carrier 8. The fixed auxiliary carrier 8 is composed of a conductive material (e.g., molybdenum), and Fig. 3b shows a state in which the thin film semiconductor wafer 1 is tested later. Embodiment 4 A thin film semiconductor wafer 1 is shown in Fig. 4, which is composed of an active layer stack 2. The conductive reflective contact material layer 4 is present on the back side of the layer stack 2. It is also strengthened by the metal strengthening layer 7. . The side surface of the thin film semiconductor wafer 1 is thus covered with a passivation layer 5 on the entire surface. Such a thin film semiconductor wafer 1 is particularly suitable for use as an electrical contact after application to a suitable wafer carrier 11 without the need for wires. ® Thus, the thin film semiconductor wafer 1 is applied to a suitable wafer carrier 11 (e.g., 'circuit board'). The wafer carrier may suitably contain a conductive structure 12 for performing back contact on the later thin film semiconductor wafer 1, and the remainder of the wafer carrier 11 is composed of an insulating material (e.g., plastic). The thin film semiconductor wafer is positioned on the conductive structure 12 of the wafer carrier 11 and then applied to the wafer carrier via the thin film semiconductor wafer 1 by applying a conductive layer 13 over the entire surface! Electrical contact is achieved on the surface of i. The conductive layer 13 is suitably formed of a material having high permeability I276235 (for example, indium tin oxide (IT 0) or zinc oxide) which emits electromagnetic radiation to the thin film semiconductor wafer 1. ^ It should be noted here that the above contact method (where no wire is required) can be considered as a separate invention. For the sake of completeness, it is to be noted that the present invention is of course not limited to the above-described embodiments. All of the embodiments which are based on the general principles of the above basic principles are within the scope of the present invention. At the same time, it should be pointed out that the different elements in the different embodiments can be combined with each other without departing from the basic idea of the invention. [Simple diagram of the diagram], Ludi La to If diagram of the wafer composite in different stages of an embodiment of the method - cutaway view. 2a to 2c are cross-sectional views of wafer composites in different stages of another embodiment of the method. 3a and 3b are cutaway views of the wafer composite in different stages of yet another embodiment of the method. Figure 4 is a cross-sectional view of a thin film semiconductor wafer of the present invention applied to a wafer carrier for electrical contact. • [Main component symbol description] 1 Thin film semiconductor wafer 2 Active layer stack 20 Active layer sequence 21 Layer composite stack 3 Growth substrate 4 Conductive reflective contact material layer 5 Passivation layer -18- 1276235 6 Flexible conductive foil 7 Metal-reinforced layer 8 Fixed auxiliary carrier 9 Conductive contact area on the front side 10 -* Foil 11 Wafer carrier 12 Conductive structure on the wafer carrier 13 Conductive layer for wafer contact -19-