Polycrystalline silicon-germanium films for integrated microsystems
Polycrystalline silicon-germanium films for integrated microsystems
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DOI：
10.1109/jmems.2002.805051
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发表时间：
2003-04-01
影响因子：
2.7
通讯作者：
Howe, RT
中科院分区：
文献类型：
--
作者：
Franke, AE;Heck, JM;Howe, RT
在完成铝金属化 CMOS 电路后，展示了两种制造微结构的方法。第一种方法采用在 400 摄氏度下沉积的 n 型多晶硅作为具有 SiO2 牺牲层和 HF 释放层的结构材料。使用非晶硅层保护 CMOS 电路免受释放蚀刻剂的影响。夹紧横向谐振器测试结构在真空中的品质因数高达 30 000。在 500°C、30 s RTA 后，多 Ge 应力为 200 MPa（拉伸），电阻率为 5.3 mΩ-cm。在第二种集成方法中，在 450°C 下沉积的 p 型多 Si0.35Ge0.65 是结构材料，多晶硅作为牺牲材料，H2O2作为释放蚀刻剂。 H2O2 不会显着蚀刻 p 型多晶 SiGe 结构层，并且不需要保护下面的 CMOS 层。首次展示了直接在标准电子器件顶部制造 LPCVD 表面微结构，从而大幅减少了 MEMS-CMOS 互连寄生效应和器件面积。折叠挠性横向谐振器在真空中的品质因数高达 15 000。无需应力或掺杂剂激活退火，因为发现原位硼掺杂多晶 SiGe 的沉积应力仅为 -10 MPa（压缩），电阻率仅为 1.8 mΩ-cm。
Two approaches were demonstrated for fabricating microstructures after completion of CMOS circuits with aluminum metallization. The first approach employed n-type poly-Ge deposited at 400degreesC as a structural material with an SiO2 sacrificial layer and an HF release. The CMOS circuits were protected from the release etchant with an amorphous Si layer. Clamped-clamped lateral resonator test structures had quality factors in vacuum as high as similar to 30 000. Following a 500degreesC, 30 s RTA the poly-Ge stress was 200 MPa (tensile) and the resistivity was 5.3 mOmega-cm.In the second integration approach, p-type poly-Si0.35Ge0.65 deposited at 450degreesC was the structural material with poly-Ge as the sacrificial material and H2O2 as the release etchant. The H2O2 did not significantly etch the p-type poly-SiGe structural layer and no protection of the underlying CMOS layers was needed. For the first time, the fabrication of LPCVD surface microstructures directly on top of standard electronics was demonstrated, providing dramatic reductions in both MEMS-CMOS interconnect parasitics and device area. A folded flexure lateral resonator had a quality factor in vacuum as high as 15 000. No stress or dopant-activation anneal was needed, since the in situ boron-doped poly-SiGe was found to have an as-deposited stress of only -10 MPa (compressive) and a resistivity of only 1.8 mOmega-cm.