Three dimensional device integration method and integrated device

An integration method, comprising:

• preparing a first element having a first layer of bondable material for direct bonding;
• providing a second layer of bondable material over the first layer of bondable material, the second layer of bondable material having a lower surface roughness than the first layer of bondable material;
• preparing a second element for direct bonding;
• bringing into direct contact the first layer of bondable material with the second element;
• directly bonding the first layer of bondable material to the second element with a covalent bond at room temperature;
• and
• after the bonding, removing a portion of the first element by one of polishing and grinding to leave a remaining portion of the first element.

An integration method, comprising:

• preparing a first element having a first layer of bondable material for direct bonding;
• preparing a second element for direct bonding;
• bringing into direct contact the first layer of bondable material with the second element;
• directly bonding the first layer of bondable material to the second element with a covalent bond at room temperature;
• and
• after the bonding, removing a portion of the first element by one of polishing and grinding to leave a remaining portion of the first element,
• wherein preparing the first element comprises preparing a first semiconductor element.